1. Field
The present embodiments relate to encapsulation and isolation for at least partially subterranean chambers of buildings.
2. Brief Description of Related Developments
Moisture is very damaging to wood structural support members of buildings and is absorbed by such members from the ground and from moist air in contact therewith.
Many buildings and homes are built without basements, and are elevated a few feet above the ground on support members such as stone, poured concrete or concrete block walls. In many cases the crawlspace between the ground surface and the wooden floor beams or joists of the house is at a level below the level of the surrounding soil, or below the level of saturated soils in wet weather, so that water flows into and is absorbed up through the floor of the crawlspace, usually a dirt surface, from adjacent ground areas of higher elevation and up from the sub-soil. Such water is drawn into the headroom of the crawl space in the form of water vapor and penetrates the wooden structural members of the building, causing wood rot, mold, odors, attraction of ants and other insects, rodents etc. Also, the escape of dangerous radon gas from the ground into the crawlspace and into the building is another problem.
Even in crawlspaces that do not leak or flood from groundwater, the earth below the crawlspace, and forming the floor of the crawlspace, has a high humidity level most of the time, and this water vapor rises into the crawlspace to produce a humid air atmosphere within the crawlspace, which moves upwardly to penetrate the structural framing and living spaces above the crawlspace.
Mold spores exist in air and grow into destructive mold in the presence of damp organic material, such as moist wood. Humidity levels of from 50% to 90% are common in crawlspaces, even those that have never flooded. Mold can grow on dirt, insulation, wood framing and even under carpeting on the floor within the home. Mold digests and destroys organic materials as it feeds on them. Damp environments also provide an inviting environment for insects such as termites, ants and similar critters that feed on moist organic material such as structural support wood and can contribute to the destruction and collapse thereof.
Vents may also be provided though the walls of the crawlspaces to allow moisture within the crawlspace to evaporate and exit the crawlspace. However, unless there is a breeze or a temperature or pressure differential between the air in the crawlspace and the atmospheric air outside the crawlspace the air will not flow in or out of the crawlspace vents. When air is flowing through the crawl space vents the volume of air exchanged through the vents may not be sufficient to prevent high humidity levels and mold growth. In addition, insects and other critters may enter and exit the crawlspace through the crawlspace vents. Outside air may also be forced, such as via a fan, into the crawlspace. This however is also unsatisfactory as exterior air is hot and humid in the summer, thereby contributing to condensation on crawlspace surfaces, and cold in winter robbing the crawlspace of insulative effectiveness.